I. Field of the Invention
This invention pertains to an apparatus for cleansing an aliphatic hydrocarbon solvent. More particularly, this invention pertains to an apparatus for cleansing a solvent of oil based contaminants having physical properties similar to those of the solvent.
II. Description of the Prior Art
In industry, aliphatic hydrocarbon solvents (such as mineral spirits and Stoddard solvents) are widely used in numerous applications. For example, in the machining industry, such solvents are used to wash machined parts of cutting and machining oil. Another use of such solvents is in the automobile service industry where the solvents are used to cleanse away motor oil and other oil based products. The solvents are used to cleanse automobile parts of oil, grease, soot, dirt, road tar, metal filings and other numerous contaminants. An example of such a solvent is the Hi-T.RTM. Degreasol.RTM. solvent marketed by Kleer-Flo Company of Eden Prairie, Minn. The solvents are aliphatic hydrocarbons having physical properties similar to those of the hydrocarbon contaminants which are being removed with the solvents. Accordingly, when the contaminants are removed by the solvents, the contaminants become widely and uniformly dispersed within the solvent.
Through use, solvents become dirty by reason of uniformly dispersed contaminants. The contaminants include a variety of elements such as fine metal particles from machine cutting tools and other particulate matter. In automobile shops, the solvents become contaminated with dissolved oil as well as a large variety of other carbon based products including free carbon particles. Also, as the solvents are repeatedly used to cleanse away oil, dissolved oil content of the solvent builds up. Accordingly, after extended use, the solvent becomes aged. As the solvent becomes used and dirty, the solvent will become obaque. Solvents are typically clear liquids which may be colored through the addition of identifying dies. Through use, the solvents become increasingly dirty such that they obtain a very dark color with the solvent liquid becoming opaque. The difference in appearance between a fresh and a used solvent is remarkable. An individual can clearly see through a vile of fresh solvent. However, after use, the solvent becomes laden with dissolved oil and takes on a muddy, thoroughly dirty, appearance that one cannot see through a vile of used solvent. When the liquid becomes opaque, operators of machine shops or other users of the solvents desire to discard the solvent (even though the opaque solvent may still be functional).
This is apparently due to the muddy appearance of the solvent which makes the solvent look completely used. Due to environmental concerns, spent solvents are generally considered hazardous materials by governmental bodies responsible for environmental protection. Specifically, their unrestricted disposition may adversely affect the environment. As a result, it is becoming increasingly costly to dispose of spent solvents. Also, disposal of a spent solvent is economically undesirable since, even though opaque, the solvent is still useful. However, it is recognized that the industry prefers clean transparent solvents.
To accommodate industry desires, methods have been developed for cleansing contaminated solvents to generate a clean transparent solvent from a dirty opaque solvent. The prior art method of cleansing a contaminated solvent was to boil the solvent in a still. Under controlled pressure and temperature, the clean solvent boils off from the dirty solvent leaving a residue of contaminants which may be separately disposed. The vaporized solvent is separately condensed and collected as a clear marketable product.
While prior art distillation methods and apparatus will produce a cleansed solvent from a contaminated solvent, the prior art methods are undesirable. For example, such stills are very expensive and present a danger of explosion and fire. Such solvents are combustible liquids (as defined in American National Standard ANSI Z129.1-1982 "combustile" means having a flash point at or above 100.degree. F. and less than 200.degree. F.). Operating these types of chemicals within high pressure and temperature stills naturally presents a danger of explosion and fire.